Novel heterocyclic compounds

ABSTRACT

The present invention relates to novel 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole compounds substituted on the nitrogen atom, to processes for producing them, to their use in agriculture for combating animal and plant pests and also for regulating plant growth, and to compositions containing these novel pyrrole compounds. 
     The novel 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole compounds substituted on the nitrogen atom correspond to the formula ##STR1## where A represents the hydroxyl group, a halogen atom or an O-acyl radical, and 
     R represents an aryl radical, an aralkyl radical, or an heteroaromatic radical which has 5-6 ring members and which is bound by way of a carbon atom.

The present invention relates to novel3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole compounds substituted onthe nitrogen atom, to processes for producing them, to their use inagriculture for combating animal and plant pests and also for regulatingplant growth, and to compositions containing these novel pyrrolecompounds.

The novel 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole compoundssubstituted on the nitrogen atom correspond to the formula ##STR2##wherein A represents the hydroxyl group, a halogen atom or an O-acylradical, and

R represents an aryl radical, an aralkyl radical, or an heteroaromaticradical which has 5-6 ring members and which is bound by way of a carbonatom.

In the definition of the formula I, the aryl radical R is anunsubstituted phenyl or naphthyl radical or a mono- or poly-substitutedphenyl or naphthyl radical, with the phenyl radical being preferred.Possible substitutents of these rings are halogen atoms, alkyl, alkoxy,or alkylthio groups, alkenyloxy, halogenoalkyl, halogenoalkenyl,alkynyl, alkynyloxy, cycloalkyl, phenyl, phenoxy or benzyloxy groups,the nitro, cyano, hydroxyl, mercapto or carboxyl radical, alkanoyl,alkoxycarbonyl, thiocarbonyl or benzoyl groups, carbamoyl radicals,alkylcarbamoyl radicals, carbamoyloxy groups, the amino group, mono-,dialkylamino or acylamino radicals, urea radicals, sulphinyl, sulphonylor sulphamoyl radicals, halogenoalkylsulphamoyl radicals, the cyanato orthiocyanato group, with the alkyl groups containing in general 1 to 4carbon atoms.

Preferred aralkyl radicals are benzyl and phenylethyl radicals radicals,the phenyl rings of which can be substituted as defined above.

The heterocyclic rings which apply in the case of R have 5 to 6 ringmembers, are aromatically unsaturated and are bound by way of a carbonatom to the 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydro-pyrrole ring. Sucha ring can be optionally substituted and can contain further heteroatoms. To be mentioned as examples are the imidazolyl, pyrazolyl,triazolyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, oxazolyl,pyridyl, pyridazyl, pyrimidyl, pyrazyl and triazinyl rings.

If these rings are further substituted, they can contain for examplehalogen atoms, lower alkyl or alkoxy groups, or a substituent such as ispossible for the aryl radical; or they can be condensed with furtherhomo- or heterocyclic rings. The following may be mentioned as examplesof condensed 5- or 6-membered hetero ring systems: benzimidazole,benzthiazole, benzoxazole, pterin, purine, quinoline, isoquinoline,naphthydrine, phthalazine, cinnoline, quinazoline and quinoxaline. Thesering systems too can be substituted.

The O-acyl radical A is a preferably aliphatic carboxylic acid radical.It can be for example an alkyl carbonate or an alkyl thiocarbamate, suchas a fatty acid radical. The fatty acid radical can be saturated orunsaturated and can contain up to 12 carbon atoms. The aliphatic radicalof this acid can be substituted by halogen atoms, or interrupted byoxygen or by the --CO group. Also applicable are cycloaliphatic radicalssuch as cyclopropyl or cyclohexyl. The O-acyl radical can also be acarbamoyloxy radical optionally mono- or disubstituted on the nitrogenatom by C₁ -C₄ -alkyl, or the benzoyl radical, which can be substitutedin the ring.

The compounds of the present invention are novel and are distinguishedby a herbicidal, and for certain compounds also fungicidal, action, andthey can be used for combating weeds or phytopathogenic fungi. Dependingon the dosage, they act either as total or selective herbicides, and canbe employed for controlling weeds in crops of cultivated plants. Othercompounds of this invention are distinguished by having an acaricidalaction, and are suitable for protecting cultivated crops or field fruitsfrom infestation by spiders, mites and similar pests.

The compounds of the present invention are negligibly toxic towarm-blooded animals, and application of these compounds presents noproblems. The amount applied is between 0.1 and 5 kg per hectare.

Some of the compounds according to the invention are likewise suitablefor regulating plant growth. They inhibit for example the growth ofmono- and dicotyledonous plants; furthermore, they promote the ripeningand abscission of fruits.

Other compounds have a defoliating action and can be used for strippingand burning off unlignified parts of plants above the soil; for examplefor facilitating the harvesting of potatoes or cotton.

The novel 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole compounds ofthe formula I are produced by reduction of a dimethyl-maleic acid imide,substituted on the nitrogen atom, of the formula II ##STR3## wherein Rhas the meaning given under the formula I, with a hydrogenating agent.

The reduction is performed at a temperature of -20°-+80° C., in asolvent, by means of a reducing agent. Suitable reducing agents aresodium hydride, lithium aluminium hydride and other metal hydrides whichgenerate hydrogen. Furthermore, catalytic hydrogenation can beperformed.

If A is not to remain the hydroxyl group, this is esterified in a knownmanner with an acid or an acid halide. The reaction of the hydroxylgroup to the halide is performed in a known manner by reaction with anacid halide such as thionyl chloride or thionyl bromide, or with anotherstrong halogenating agent, e.g. phosphorus oxychloride and phosphorusoxybromide, or phosphorus pentachloride and phosphorus pentabromide,respectively. An O-acyl group A can be introduced into the 2-position ofthe pyrrole ring by esterifying, in a known manner, the hydroxyl grouppresent in this position with a carboxylic acid derivative; or byreacting a halogen atom present there with a carboxylic acid derivative.

The compounds of the formula I can be used as such, or as salts isolatedwith strong organic or inorganic acids.

The solvents used can be lower alkanols, ethers or tetrahydrofuran andalso water. The said reductions can be performed under normal pressurein customary apparatus.

Some of the dimethyl-maleic acid imides of the formula II are knowncompounds, the production of which is described in the GermanOffenlegungsschrift No. 2,233,889, in the French Pat. No. 2,145,618 orin the British patent specification No. 1,390,649. They can be obtainedin good yields by reacting, for example, 2 moles of fumaric acid ormaleic acid, at a temperature of above 70° C., with at least one mole ofan amidine of the formula III ##STR4## to give a compound of the formulaIV ##STR5## in which formulae the symbol X together with the grouping##STR6## forms the radical of a 5- or 6-membered, optionally furthersubstituted, heterocycle which can contain further hetero atoms,especially S, N or O.

The ring, which is formed in the compound of the formulae III and IV byX together with the grouping ##STR7## can already correspond to theradical R of the formulae I and II if compounds in which R represents anitrogen-containing unsaturated 5-6-membered heterocycle are desired. Ifcompounds having another radical R are desired, the compound of theformula IV can be hydrolysed by an acid medium to give2,3-dimethyl-maleic acid anhydride, which can then be easily condensedwith a primary amine of the formula V

    r -- nh.sub.2                                              (v),

wherein R has the meaning given under the formula I, in the melt or inan inert solvent, directly to the imide of the formula II.

The following Examples illustrate the processes for producingarbitrarily selected active substances of the formula I. Other activesubstances, produced in a corresponding manner, are listed in the Tableswhich follow. Temperature values are in every case in degreesCentigrade.

EXAMPLE 1 N-(2'-Pyridyl)-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole

20.2 g (0.1 mole) of N-(2-pyridyl)-dimethyl-maleimide is suspended in200 ml of methanol and the suspension is cooled. There is thenintroduced portionwise at an internal temperature of 0°-5° in the courseof 2 hours, with stirring, 1.9 g (0.05 mole) of NaBH₄. The reaction isfinished after one hour with stirring at room temperature. An additionof 100 ml of H₂ O is made with cooling, and the methanol is subsequentlydistilled off in a rotary evaporator at a bath temperature of 50°. Theproduct commences to crystallise during distillation, and the crystalsare finally filtered off under suction and afterwashed with 50 ml of H₂O.

Yield: 18.5 g, m.p. 101°-102°; 91% of theory (compound No. 1, in TableII).

EXAMPLE 2N-(3'-methylphenyl)-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole

26.2 g (0.2 mole) of dimethylmaleic acid anhydride is put together with21.4 g (0.2 mole) of 3-toluidine, and the whole is heated to 130°, withwater distilling off at this temperature. After about 1 hour, the cooledreaction mixture is dissolved in methanol and the solution is cooled to0°. The product crystallises during cooling, and is filtered off anddried to give light-yellow crystals having a melting point of 83°-84°.The yield is 35 g (81.4% of theory).

To 20 g (0.93 mole) of the resultingN-(3-methylphenyl)dimethyl-maleimide in 180 ml of methanol is added at20° 7.2 g (0.185 mole) of sodium borohydride in portions so small thatthe temperature does not exceed 40°. An intense evolution of gas isobserved. The reaction mixture is initially a clear colourless solution,but soon becomes a white suspension, which is poured after one hour intowater. The white substance which has precipitated out is filtered off,washed well with methanol and dried under reduced pressure to obtain18.6 g of white crystals (92.1% of theory), which melt at 170°-172°(compound No. 9, Table I).

EXAMPLE 3N-(3',4'-Dichlorophenyl)-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole

In a manner analogous to that of Example 2, 26.2 g (0.2 mole) ofdimethylmaleic acid anhydride and 32.6 g (0.2 mole) of3,4-dichloroaniline are condensed to giveN-(3,4-dichlorophenyl)dimethyl-maleimide, which is then dissolved in 300ml of methanol. To this solution is slowly added in portions, withstirring, 10.8 g of sodium borohydride. After the addition is completeand the generation of gas has subsided, the reaction mixture is pouredinto ice water. The white precipitate is filtered off, washed withmethanol and dried. There is obtained 49.3 g (84% of theory) of theabove product in the form of colourless crystalline powder, m.p. 188°.

EXAMPLE 4N-(5'-methylpyrid-2'-yl)-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole

21.6 g (0.1 mole) of N-(5'-methylpyrid-2'-yl)-dimethylmaleimide issuspended in 200 ml of toluene, and the suspension with 1 g of an RuCl₂[P(C₆ H₅)₃ ]₂ catalyst is placed into a hydrogenating autoclave andhydrogenated at 100°-110° under 30-50 bars. The theoretical amount ofhydrogen has been absorbed after 2-5 hours. The reaction mixture isseparated from the catalyst by filtration, and the filtrate isevaporated to dryness under reduced pressure. The residue isrecrystallised from ethyl acetate to yield 16.4 g (75% of theory) of theabove compound in the form of colourless crystals, m.p. 118°-119°.

EXAMPLE 5N-(3',4'-dichlorophenyl)-3,4-dimethyl-2-acetoxy-5-oxo-2,5-dihydropyrrole

27.2 g ofN-(3',4'-dichlorophenyl-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole(see Example 3) is refluxed together with 20.7 g of K₂ CO₃ in 150 ml ofmethyl ethyl ketone. After cooling, there is added dropwise 8.2 g ofacetyl chloride, with the temperature of the reaction mixture risingfrom 15° to 35°. The reaction mixture is filtered after 24 hours, andthe filtrate is concentrated by evaporation. The residue isrecrystallised from methanol to give 23.9 g (76% of theory) of the aboveproduct in the form of colourless crystals, m.p. 109°-110°.

EXAMPLE 6N-(3',4'-Dichlorophenyl)-3,4-dimethyl-2-chloro-5-oxo-2,5-dihydropyrrole

27.2 g ofN-(3',4'-dichlorophenyl)-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole(see Example 3) is added to 25 ml of thionyl chloride, with an intenseevolution of gas occurring. After being stirred for one hour at 50°, themixture is concentrated by evaporation in vacuo. The solid residue istriturated with petroleum ether to obtain 27.4 g (95% of theory) of theabove compound in the form of light-yellow crystals, m.p. 95°-96°.

EXAMPLE 7N-(3',4'-Dichlorophenyl)-3,4-dimethyl-2-fluoro-5-oxo-2,5-dihydropyrrole

23.2 gN-(3,4-dichlorophenyl)-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole(see Example 3) is refluxed together with 11.6 g of potassium fluorideand 0.3 g of 18-crown-6 (cyclic polyethylene ether) in 50 ml ofacetonitrile for 14 hours. After cooling, undissolved constituents arefiltered off, and the filtrate is concentrated by evaporation. Theresidue is recrystallised from methanol to yield 8 g (35% of theory) ofthe above product in the form of colourless crystals, m.p. 102°-103°.

EXAMPLE 8N-(3',4'-Dichlorophenyl)-3,4-dimethyl-2-methyl-carbamoyloxy-5-oxo-2,5-dihydropyrrole

16.3 g ofN-(3',4'-dichlorophenyl)-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole(see Example 3) is put together with 2 drops of triethylamine in 10 mlof glyme (ethylene glycol dimethyl ether), and 3.8 g of methylisocyanateis then added. After 24 hours, the reaction solution is filtered with afiltering auxiliary (Hyflo®) and the filtrate is concentrated byevaporation to leave an oil, which is crystallised in methanol. In thismanner is obtained 15 g (76% of theory) of the above product in the formof yellowish crystals, m.p. 141°-142°.

EXAMPLE 9N-(5'-Methyl-pyrid-2'-yl)-3,4-dimethyl-2-acetoacetoxy-5-oxo-2,5-dihydropyrrole

15.3 g ofN-(5'-methyl-pyrid-2'-yl-3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole(see Example 4) and 5.9 g of diketene together with 20 ml of benzene aremaintained for 5 hours at 50°. A further 3 g of diketene is then addedand the reaction mixture is held at 50° for 4 hours. It is thenconcentrated by evaporation, and the residue is crystallised fromacetonitrile to obtain 14.5 g (68% of theory) of the above product ascolourless crystals, m.p. 112°-115°.

                                      Table I                                     __________________________________________________________________________     ##STR8##                                                                     Com-                                                                          pound                            Melting                                      No. R                 A          point                                        __________________________________________________________________________    1   phenyl            OH         129°                                  2   3,4-dichlorophenyl                                                                              OH         188°                                  3   3,5-dichlorophenyl                                                                              OH         188°                                  4   4-chloro-3-trifluoromethylphenyl                                                                OH         160°                                  5   4-fluorophenyl    OH         168°                                  6   2,6-dimethylphenyl                                                                              OH         169°                                  7   4-methylphenyl    OH         193-194°                              8   2-nitrophenyl     OH         147°                                  9   3-methylphenyl    OH         170-172°                              10  4-phenoxyphenyl   OH         165-167°                              11  diphenyl          OH         218-220°                              12  3-chloro-4-methylphenyl                                                                         OH         207-208°                              13  3,4-dimethylphenyl                                                                              OH         166-168°                              14  4-dimethylaminophenyl                                                                           OH         200-202°                              15  4-bromophenyl     OH         178-179°                              16  4-chlorophenyl    OH         178-180°                              17  3-methoxyphenyl   OH         137-138°                              18  4-benzoylphenyl   OH         146-150°                              19  4-trifluoromethylphenyl                                                                         OH         201-202°                              20  4-methoxyphenyl   OH         148-149°                              21  4-methyl-3-nitrophenyl                                                                          OH         195-196°                              22  3-chloro-4-methoxyphenyl                                                                        OH         171-172°                              23  4-acetamidophenyl OH         268-269°                              24  4-chloro-2-methylphenyl                                                                         OH         154- 155°                             25  2-fluorophenyl    OH         124-126°                              26  3-carboxyl-4-chlorophenyl                                                                       OH         270° decomp.                          27  2-hydroxyphenyl   OH         148°                                  28  4-hydroxyphenyl   OH         169°                                  29  3,5-bis-(trifluoromethyl)phenyl                                                                 OH         152-154°                              30  3-trifluoromethylphenyl                                                                         OH         192-193°                              31  3-chlorophenyl    OH         174-175°                              32  3-bromophenyl     OH         182-183°                              33  3-hydroxyphenyl   OH         223-224°                              34  3-nitrophenyl     OH         182-183°                              35  3-methylthiophenyl                                                                              OH         145-146°                              36  3-methylcarbamoyloxyphenyl                                                                      OH         167 zers                                     37  3-mercaptophenyl  OH         103-105°                              38  3-carboxyphenyl   OH         215° decomp.                          39  3-ethylphenyl     OH         132-133°                              40  3-sulphamoylphenyl                                                                              OH         146-147°                              41  4-nitrophenyl     OH         241° decomp.                          42  3-t.butylcarbamoyloxyphenyl                                                                     OH         173-175°                              43  3-aminophenyl     OH         149-150°                              44  benzyl            OH         102°                                  45  2-chlorobenzyl    OH         170°                                  46  3-chlorobenzyl    OH         120°                                  47  4-chlorobenzyl    OH         115°                                  48  3-amino-4-methylphenyl                                                                          OH         172-173°                              49  α-phenylethyl                                                                             OH         100°                                  50  4-methylbenzyl    OH         127°                                  51  4-methoxy-3-trifluoromethylphenyl                                                               OH         186-188°                              52  3-chloro-4-trifluoromethylphenyl                                                                OH         187-189°                              53  4-(4'-chlorophenoxy)-phenyl                                                                     OH         167-168°                              54  4-ethoxy-3-trifluoromethylphenyl                                                                OH         173-175°                              55  3-chloro-4-fluorophenyl                                                                         OH         188-190°                              56  4-fluoro-3-trifluoromethylphenyl                                                                OH         175-177°                              57  3,4-dimethoxyphenyl                                                                             OH         158-159°                              58  3,4-dichlorophenyl                                                                              Cl         95-96°                                59  3,4-dichlorophenyl                                                                              F          102-103°                              60  3,4-dichlorophenyl                                                                              OCOCH.sub.3                                                                              109-110°                              61  3,4-dichlorophenyl                                                                              OCONHCH.sub.3                                                                            141-142°                              62  3-methylphenyl    OCOCH.sub.3                                                                              oil                                          63  3-methylphenyl    OCONHCH.sub.3                                                                            135-137°                              64  3-methylphenyl    OCOCHCH.sub.2                                                                            oil                                          65  3-methylphenyl    OCOCHCHCH.sub.3                                                                          oil                                          66  3-methylphenyl    OCOCH.sub.2 COCH.sub.3                                                                   82-83°                                67  3-nitrophenyl     OCOCH.sub.3                                                                              123-125°                              68  4-nitrophenyl     OCONHCH.sub.3                                                                            174-175°                              69  3-methylthiophenyl                                                                              OCONHCH.sub.3                                                                            94-95°                                70  3-chloro-4-trifluoromethylphenyl                                                                OCOCH.sub.2 COCH.sub.3                                                                   108-109°                              __________________________________________________________________________

                                      table II                                    __________________________________________________________________________    R = heterocyclic radical                                                      Compound                            Melting                                   No.       R               A         point                                     __________________________________________________________________________    1     2-pyridyl           OH        101-102°                           2     2-thiazolyl         OH        123°                               3     3-hydroxy-2-pyridyl OH        111°                               4     5-chloro-2-pyridyl  OH        139°                               5     5-methyl-2-pyridyl  OH        122°                               6     4,6-dimethyl-2-pyrimidyl                                                                          OH        181°                               7     3-methyl-2-pyridyl  OH        188°                               8     4-pyridyl           OH        214°                               9     5-nitro-2-pyridyl   OH        214°                               10    3-pyridyl           OH        180°                               11    6-methyl-2-pyridyl  OH        115°                               12    4-methyl-2-pyridyl  OH        112°                               13    5-methylthio-1,3,4-thiadiazol-2-yl                                                                OH        201-02°                            14    5-trifluoromethyl-1,3,4-thiadiazol-2-yl                                                           OH        173-14°                            15    4-t.butyl-thiazol-2-yl                                                                            OH        94°-95°                     16    4-methyl-thiazol-2-yl                                                                             OH        168-169°                           17    1,3-dimethylpyridazol-6-yl                                                                        OH        191-192°                           18    6-hydroxy-pyrazin-3-yl                                                                            OH        230-233°                           19    2-pyridyl HCl       OH        205° decomp.                       20    2-pyrazine          OH        128-129°                           21    2,6-dimethylpyrimidin-3-yl                                                                        OH        178-179°                           22    6-acetamidopyrid-2-yl                                                                             OH        199°                               23    (3'-pyridyl)-methyl OH        110°                               24    (4'-pyridyl)-methyl OH        143°                               25    5-acetamido-pyrid-2-yl                                                                            OH        286°                               26    4,6-dimethyl-pyrid-2-yl                                                                           OH        116°                               27    5-methyl-oxal-2-yl  OH        167-168°                           28    3-methyl-(1'2'4'-thiadiazol)-5-yl                                                                 OH        173-175°                           29    4-amino-5-cyano-6-piperidyl-                                                  pyrid-2'-yl         OH        >280° decomp.                      30    6-amino-pyrid-2-yl . HCl                                                                          OH        263°                               31    2-(indol-3'-yl-ethyl                                                                              OH        175°                               32    3-hydroxy-5-chlor-pyrid-2-yl                                                                      OH        166°                               33    3-methoxy-pyrid-2-yl                                                                              OH        159°                               34    4-ethyl-pyrid-2-yl  OH        59°                                35    4-tert.butyl-pyrid-2-yl                                                                           OH        87°                                36    2-pyridyl           OCONHCH.sub.3                                                                           140-141°                           37    2-pyridyl           OCOCH.sub.2 COCH.sub.3                                                                  114-115°                           38    2-pyridyl           OCOCHCH.sub.2 CH.sub.3                                                                  106-107°                           39    2-pyridyl                                                                                          ##STR9## 143-145°                           40    2-pyridyl           OC.sub.2 H.sub.4 Cl                                                                     125-126°                           41    2-pyridyl           OCOOC.sub.2 H.sub.5                                                                     63-65°                             42    2-pyridyl                                                                                          ##STR10##                                                                              130-131°                           43    5-methyl-pyrid-2-yl OCOCH.sub.2 COCH.sub.3                                                                  130-131°                           44    5-methyl-pyrid-2-yl OCOCH.sub.3                                                                             109-110°                           45    5-methyl-pyrid-2-yl OCOCH.sub.2 Cl                                                                          113-115°                           46    5-methyl-pyrid-2-yl OCOOC.sub.2 H.sub.5                                                                     117-119°                           47    5-methyl-pyrid-2-yl                                                                                ##STR11##                                                                              136-137°                           48    5-methyl-pyrid-2-yl OCONHCH.sub.3                                                                           153-154°                           49    5-methyl-pyrid-2-yl OCON(CH.sub.3).sub.2                                                                    147-148°                           50    5-methyl-pyrid-2-yl OCOCHCHCH.sub.3                                                                         95-96°                             51    5-methyl-pyrid-2-yl OCOSC.sub.2 H.sub.5                                                                     91-92°                             52    5-methyl-pyrid-2-yl OCOtert . C.sub.4 H.sub.9                                                               114-115°                           53    5-methyl-pyrid-2-yl                                                                                ##STR12##                                                                              119- 120°                          54    5-methyl-pyrid-2-yl OCOisoC.sub.3 H.sub.7                                                                   87-88°                             55    5-methyl-pyrid-2-yl . HCl                                                                         Cl        177-178° decomp.                   56    5-methyl-pyrid-2-yl                                                                                ##STR13##                                                                              79-80°                             57    4-t.butyl-thiazol-2-yl                                                                            OCONHCH.sub.3                                                                           146-147°                           __________________________________________________________________________

the novel 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole compounds ofthe formula I have a versatile spectrum of activity, and are thereforeexcellently suitable for combating plant and animal pests, or forregulating plant growth. The effectiveness was determined by the testsdescribed in the following Examples.

EXAMPLE 10 Herbicidal action with application of the active substancesbefore emergence (pre-emergence) of the plants

Immediately after sowing of the test plants, the surface of the soil istreated with an aqueous suspension, obtained from 25% wettable powders,of the active substances. The amount applied is chosen to be equivalentto 16 kg and 4 kg of active substance per hectare. The seed trays arekept in a greenhouse at 22°-25° C. with 50-70% relative humidity.

The following are used as test plants:

Avena sativa

Setaria italica

Sinapis alba

Stellaria media

The test is evaluated 20 days after application of the activesubstances.

The evaluation is made on the basis of the following scale of valuesfrom 1 to 9:

1 = plants dead,

2-4 = intermediate stages of damage (over 50% irreversible damage),

5-8 = intermediate stages of damage (below 50% irreversible damage),

9 = plants undamaged (control).

EXAMPLE 11 Herbicidal action with application of the active substancesafter emergence (post-emergence) of the plants

The test plants are treated in the 2-4-leaf stage with aqueoussuspensions (obtained from 25% emulsion concentrates) of the activesubstances. The amount applied corresponds to 4 kg of active substanceper hectare.

The following are used as test plants:

Avena sativa

Setaria italica

Lolium perenne

Solanum lycopersianum

Sinapis alba

Stellaria media

Gossypium hirsutum

Phaseolus vulgares

The plants are kept after the treatment for 14 days in a greenhouseunder normal conditions, and the evaluation is then made on the basis ofthe scale of values from 1 to 9 as in Example 10.

EXAMPLE 12 Growth reduction in the case of grasses (Application afteremergence of the plants (post-emergence))

Seeds of the grass varieties Lolium perenne, Poa pratensis, Festucaovina and Dactylis glomerata are sown in plastic dishes containing asoil/peat/sand mixture. After 3 and 4 weeks, the emerged grasses are cutback to 4 cm above the soil, and 2 days after the second cutting aresprayed with aqueous spray liquors containing the active substance. Theamount of active substance is equivalent to 5 kg of active substance perhectare. Fourteen days after application, the growth of the grasses isevaluated according to the following linear scale of ratings:

1 = severe reduction, no growth after application;

9 = no reduction, growth as in the case of the control specimens.

EXAMPLE 13 Action against Fusarium oxysporum on Solanum lycopersicum

(a) Action after soil treatment

Tomato plants are damaged at the roots after cultivation for 3 weeks andare then infested with a spore suspension of the wilt pathogen. After 24hours, a spray liquor produced from wettable powder of the activesubstance is poured around the infested tomato plants (60 ppm relativeto the final liquor volume). After an incubation period of 14 days in agreenhouse at about 22° C., the degree of wilt of the plants isassessed.

(b) Action after leaf treatment

After 3-weeks' cultivation, the roots of tomato plants are damaged andthe plants infested with a spore suspension of the wilt pathogen. After24 hours, the plants are sprayed with a spray liquor (0.18% of activesubstance) prepared from wettable powder of the active substance. Afteran incubation period of 14 days in a greenhouse at about 22° C., thedegree of wilt of the infested tomato plants is determined.

EXAMPLE 14 Action against red spider mites

Bush bean plants (Phaseolus vulgaris) are infested in the two-leafstage, 12 hours before treatment with the active substance, with redspider mites by placing onto the plants infested pieces of leaf from aculture, so that after this period of time (12 hours) there is presenton the plants a population in all stages of development. The plants arethen sprayed with the emulsified active substance using a chromatographysprayer until a uniform coating of droplets is formed on the surface ofthe leaves. An evaluation is made after 2 and 7 days: the parts of theplants are examined under a stereomicroscope in order to calculate themortality percentages.

EXAMPLE 15 Growth reduction in soya bean crops

Smallish plots sown with soya bean plants are sprayed in the blossomperiod with an aqueous preparation of one of the compounds according tothe invention, and this treatment is repeated 5 times in each test. Atthe same time, control plots are left untreated. At the point of timefor harvesting, the mean height of growth of the plants and the yield isdetermined for each plot.

EXAMPLE 16 Dessication and defoliation of cotton plants

Cotton plants of the variety "Delta Pine" are grown in a greenhouse, andare sprayed after blossoming using aqueous suspensions of the givenactive substances. The concentration of active substance in the sprayliquor is 1%, and 20 ml of liquor is sprayed on. Plants treated withwater only are used as control plants. Fourteen days after application,the plants are evaluated with respect to defoliation and dessication.The following rating system is used for this purpose:

rating 9 = 0 to 11% defoliation and dessication,

rating 8 = 12 to 22% defoliation and dessication,

rating 7 = 23 to 33% defoliation and dessication, and

rating 1 = 89 to 100% defoliation and dessication.

The compositions according to the invention are produced in a mannerknown per se by the intimate mixing and/or grinding of active substancesof the general formula I with suitable carriers, optionally with theaddition of dispersing agents or solvents which are inert to the activesubstances. The active substances can be obtained and used in thefollowing forms:

solid preparations: dusts, scattering agents, granules (coated granules,impregnated granules and homogeneous granules;

active-substance concentrates dispersible in water: wettable powders,pastes and emulsions;

liquid preparations: solutions.

The solid preparations (dusts, scattering agents and granules) areproduced by mixing the active substances with solid carriers. These canbe, e.g., kaolin, talcum, bole, loess, chalk, limestone, groundlimestone, Attaclay, dolomite, diatomaceous earth, precipitated silicicacid, alkaline-earth silicates, sodium and potassium aluminium silicates(feldspars and mica), calcium and magnesium sulphates, magnesium oxide,ground synthetic materials, fertilisers such as ammonium sulphate,ammonium phosphate, ammonium nitrate, urea, ground vegetable productssuch as bran, bark dust, sawdust, ground nutshells, cellulose powder,residues of plant extractions, active charcoal, etc., alone or inadmixture with each other.

The particle size of the carriers is for dusts advantageously up toabout 0.1 mm; for scattering agents about 0.075 to 0.2 mm; and forgranules 0.2 mm or coarser.

The concentration of active substance in the solid preparations is 0.5to 80%.

It is possible to add to these mixtures also additives stabilising theactive substance, and/or nonionic, anion-active and cation-activesubstances which improve, e.g., the adhesiveness of the activesubstances on plants and parts of plants (adhesives and agglutinants),and/or ensure better wettability (wetting agents) and alsodispersibility (dispersing agents). Suitable adhesives are, for example,olein/lime mixtures, cellulose derivatives (methyl cellulose,carboxymethyl cellulose), hydroxyethylene glycol ethers or monoalkyl anddialkyl phenols having 5 to 15 ethylene oxide radicals per molecule and8 to 9 carbon atoms in the alkyl radical, ligninsulphonic acid, thealkali metal salts and alkaline-earth metal salts thereof, polyethyleneglycol ethers (carbowaxes), fatty alcohol polyglycol ethers having 5 to20 ethylene oxide radicals per molecule and 8 to 18 carbon atoms in thefatty alcohol moiety, condensation products of ethylene oxide, propyleneoxide, polyvinylpyrrolidones, polyvinyl alcohols, condensation productsof urea and formaldehyde, and also latex products.

Water-dispersible concentrates of active substances, e.g. wettablepowders, pastes and emulsion concentrates, are agents which can bediluted with water to give the desired concentration. They consist ofactive substance, carrier, optionally additives stabilising the activesubstance, surface-active substances, and antifoaming agents and,optionally, solvents. The concentration of active substance in thesepreparations is 5-80%.

The wettable powders and pastes are obtained by mixing and grinding theactive substances with dispersing agents and pulverulent carriers, insuitable devices, until homogeneity is obtained. Suitable carriers are,e.g., those previously mentioned in the case of said preparations. It isadvantageous in some cases to use mixtures of different carriers. Asdispersing agents it is possible to use, e.g.: condensation products ofsulphonated naphthalene and sulphonated naphthalene derivatives withformaldehyde, condensation products of naphthalene or ofnaphthalenesulphonic acids with phenol and formaldehyde, and also alkalimetal salts, ammonium salts and alkaline-earth metal salts ofligninsulphonic acid, also alkylarylsulphonates, alkali metal salts andalkaline-earth metal salts of dibutyl-naphthalenesulphonic acid, fattyalcohol sulphates such as salts of sulphated hexadecanols,heptadecanols, octadecanols, and salts of sulphated fatty alcohol glycolethers, the sodium salt of oleyl methyl tauride, ditertiary acetyleneglycols, dialkyl dilauryl ammonium chloride, and fatty acid alkali-metaland alkaline-earth-metal salts.

Suitable antifoaming agents are, for example, silicones.

The active substances are mixed, ground, sieved and strained with theabove-mentioned additives until the solid constituent in the case ofwettable powders has a particle size not exceeding 0.02 to 0.04 mm, andin the case of pastes not exceeding 0.03 mm. For the preparation ofemulsion concentrates and pastes, dispersing agents are used such asthose mentioned in the preceding paragraphs, organic solvents and water.Suitable solvents are, e.g., alcohols, benzene, xylenes, toluene,dimethylsulphoxide, N,N-dialkylated amides, N-oxides of amines,especially trialkylamines, and mineral oil fractions boiling in therange of 120° to 350° C. The solvents must be practically odourless,nonphytotoxic, inert to the active substances and not readilycombustible.

Furthermore, the compositions according to the invention can be used inthe form of solutions. For this purpose, the active substance, orseveral active substances, of the general formula I is (or are)dissolved in suitable organic solvents, solvent mixtures, water, ormixtures of organic solvents with water. As organic solvents, it ispossible to use aliphatic and aromatic hydrocarbons, their chlorinatedderivatives, alkylnaphthalenes, mineral oils on their own or inadmixture with each other. The solutions should contain the activesubstances at a concentration of 1 to 20%.

These solutions can be applied either by means of a propellant gas (asspray), or by means of special sprayers (as aerosol).

Other biocidal active substances or agents can be mixed with thedescribed compositions according to the invention. For the broadening oftheir sphere of action, the novel compositions can for example contain,in addition to the stated compounds of the general formula I, otherherbicides, and also fungicides, bactericides, fungistatics,bacteriostatics or nematocides. The compositions according to theinvention can also contain fertilisers, trace elements, etc.

Preparations of the novel active substances of the general formula I aredescribed in the following. Parts are given as parts by weight.

Wettable powders

The following constituents are used to produce (a) a 40%, (b) and (c) a25%, and (d) a 10% wettable powder:

(a) 40 parts of active substance,

5 parts of sodium lignin sulphonate,

1 part of sodium dibutyl-naphthalene sulphonate,

54 parts of silicic acid;

(b) 25 parts of active substance,

4.5 parts of calcium lignin sulphonate,

1.9 parts of Champagne chalk/hydroxyethyl cellulose mixture (1:1),

1.5 parts of sodium dibutyl-naphthalene sulphonate,

19.5 parts of silicic acid,

19.5 parts of Champagne chalk,

28.1 parts of kaolin;

(c) 25 parts of active substance,

2.5 parts of isooctylphenoxy-polyoxyethylene-ethanol,

1.7 parts of Champagne chalk/hydroxyethyl cellulose mixture (1:1),

8.3 parts of sodium aluminium silicate,

16.5 parts of kieselguhr,

46 parts of kaolin;

(d) 10 parts of active substance,

3 parts of a mixture of the sodium salts of saturated fatty alcoholsulphates,

5 parts of naphthalenesulphonic acid/formaldehyde condensate,

82 parts of kaolin.

The active substances are intimately mixed in suitable mixers with theadditives, and the mixture is then ground in the appropriate mills androllers to give wettable powders which can be diluted with water toobtain suspensions of the desired concentration.

Emulsifiable concentrates

The following substances are used to produce (a) a 10% and (b) a 25%emulsifiable concentrate:

(a) 10 parts of active substance,

3.4 parts of epoxidised vegetable oil,

3.4 parts of a combination emulsifier consisting of fatty alcoholpolyglycol ether and alkylarylsulphonate calcium salt,

40 parts of dimethylformamide,

43.2 parts of xylene; and

(b) 25 parts of active substance,

2.5 parts of epoxidised vegetable oil,

10 parts of an alkylarylsulphonate/fatty alcohol polyglycol ethermixture,

5 parts of dimethylformamide,

57.5 parts of xylene.

Emulsions of the concentration desired can be prepared from theseconcentrates by dilution with water.

We claim:
 1. 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydropyrrole compoundsof the formula I ##STR14## wherein A represents the hydroxyl group, ahalogen atom or an O-acyl radical, andR represents a pyridyl radicalwhich is bound by way of a carbon atom and may be substituted byhalogen, lower alkyl, lower alkoxy, hydroxy, nitro, amino, cyano, C₁ -C₄alkylcarbonylamino and piperidine.
 2. The compounds of the formula I,claim 1, wherein A represents the OH group.
 3. The compounds of theformula I, claim 1, wherein R represents a 2-pyridyl radical.
 4. Thecompound 3,4-dimethyl-2-hydroxy-1-(5'-methyl-pyrid-2'-yl)-5-oxo-pyrroleaccording to claim
 1. 5. The compound,3,4-dimethyl-2-hydroxy-1-(4'-methyl-pyrid-2'-yl)-5-oxy-pyrrole,according to claim
 1. 6. The compound,3,4-dimethyl-2-hydroxy-5-oxo-1-(pyrid-2'-yl)-pyrrole hydrochloride,according to claim
 1. 7. The compound,1-(4'-ethyl-pyrid-2'-yl)-3,4-dimethyl-2-hydroxy-5-oxo-pyrrole, accordingto claim
 1. 8. The compound,1-(4'-tert.-butyl-pyrid-2'-yl)-3,4-dimethyl-2-hydroxy-5-oxo-pyrrole,according to claim
 1. 9. Composition for combating plant and animalpests, which composition contains as active substance a pesticidallyeffective amount of a 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydro-pyrrolecompound of the formula I, claim 1, together with a suitable carriertherefor.
 10. A method for combating plant and animal pests whichcomprises applying to the locus thereof a pesticidally effective amountof 3,4-dimethyl-2-hydroxy-5-oxo-2,5-dihydro-pyrrole compound of theformula I, claim 1.